1. Field of the invention
This invention relates to a target slippage ratio setting device mounted on a vehicle like a motorcycle or car, for setting a slippage ratio for optimum braking.
2. Description of the Related Art
Brake control systems for motor vehicles are known which compare the peripheral speed of each wheel of a vehicle under braking and traveling conditions, and controls the braking based on the result of comparison. In this type of brake control system, a slippage ratio is calculated based on the peripheral velocity of each wheel and the velocity of the vehicle. When the slippage ratio reaches or exceeds a target slippage ratio at which the optimum braking is carried out, the hydraulic pressure of the brake is reduced. In this condition, the peripheral velocity of each wheel is controlled so as to reduce the slippage ratio, thereby obtaining a satisfactory braking force. In this case, the target slippage ratio is set depending on a coefficient of friction of a road surface.
If the target slippage ratio is established taking into account information about the behavior of the vehicle or other information other than the coefficient of friction of the road surface, then further control of braking can be carried out. Information about the vehicle's banking angle (i.e. the angle of inclination of the vehicle from the vertical in a direction perpendicular to the traveling direction of the vehicle), may be input to the conventional brake control system to control in a more satisfactory manner. An example is disclosed in Japanese Patent Application Laid-Open Publication No. 63-258254. Thus, there has been a demand for a system for setting a target slippage ratio based on the information about the behavior of the vehicle.